Reports from the CoMix social contact survey
Multiple members of CMMID are working on the ongoing Covid-19 (previously referred to as novel coronavirus or nCov) outbreak caused by the SARS-CoV-2 virus. This page shows an overview of our work. We regularly update this page with new and updated work.
Our group has made multiple interactive applications where some of our work can be explored further.
We also translated some of our posts in Chinese: 中文版
The list below shows all our work on this topic. To only show studies for a specific topic, select from the adjacent listlist above.
Using a model of individual infectiousness and testing with lateral flow tests (LFT), we evaluate test-to-release policies against conventional fixed-duration isolation policies in terms of excess days of infectiousness, days saved, and tests used.
We model the potential consequences of the Omicron SARS-CoV-2 variant on transmission and health outcomes in England.
We evaluated the cost-effectiveness of vaccination against COVID-19 in Sindh, Pakistan
We estimated population changes in the UK using the location of Facebook users and show how time-varying populations influence a model of COVID-19.
We fitted a dynamic transmission model to satellite imagery of the main cemeteries in Mogadishu (Somalia) that showed an unexplained and sustained rise of burials in the period of late February to July 2020. Under the assumption that these excess deaths in Mogadishu were directly attributable to SARS-CoV-2 infection we arrived at median estimates of October-November 2019 for the date of introduction and low R0 estimates (1.3-1.5), stemming from the early and slow rise of excess deaths and their long plateau. Subject to study assumptions, a very early SARS-CoV-2 introduction event may have occurred in Somalia, while showing lower transmissibility in the first epidemic wave than observed in European settings.
We evaluate the utility of pre and post-flight PCR and lateral flow testing (LFT) to reduce transmission risk from infected arrivals and to reduce the duration of, or replace, quarantine. We also estimate the effectiveness of each strategy relative to domestic incidence, and limits of achievable risk reduction, for 99 countries where flight data and case numbers are estimated.
Analysis of B.1.617.2 dynamics in the UK.
We present one full year of CoMix contact survey data from participants in England between March 2020 and March 2021 to track social contact behaviour during the Covid-19 pandemic.
Analysis of SARS-CoV-2 reinfection risk in a workplace cohort in the United States.
Comment piece on the feasibility of reaching the herd immunity threshold against SARS-CoV-2, drawing comparisons with other vaccine-preventable pathogens.
We show that the relative hazard of death in community-detected cases of SARS-CoV-2 in England is 55% higher in individuals infected with the B.1.1.7 variant.
Estimating the effect of using a follow-up PCR or lateral-flow test (LFT) upon a positive initial LFT in the mass asymptomatic testing of students in England.
Estimating a lower bound on test specificity using published data on LFD testing in educational settings
Combining multiple behavioural and epidemiological data sources with mathematical models, we analysed the transmissibility and impact of novel SARS-CoV-2 Variant of Concern 202012/01 in England.
We present the analyses of the impact of national and local restrictions on the number of setting-specific contacts that people have prior to and during the restrictions from an ongoing survey (CoMix) which tracks social contact behaviour during the Covid-19 pandemic.
Combining CoMix contact survey data with profiles in infectiousness and susceptibility to estimate the effect on the reproduction number.
A second wave of COVID-19 cases in Autumn 2020 led to localised, tiered “Alert Level” restrictions and subsequently a second national lockdown in England. We examine the impact of these tiered restrictions and options for lockdowns in terms of stringency, timing and length.
We evaluate the ability of different quarantine and testing strategies to reduce the transmission potential of traced secondary cases, accounting for PCR and lateral-flow antigen test sensitivities, test and trace delays, and varying levels of adherence.
Using hospital and national level data, we describe the sequence of hospital beds occupied by patients with COVID-19. Our results suggest that national LoS averages may not be appropriate for local forecasts of bed occupancy for COVID-19.
Using globally available data sources with mathematical models, we analysed the transmissibility and severity of a novel SARS-CoV-2 variant, 501Y.V2, in South Africa.
Exploring the relationship between the proportion of samples with S-gene target failure and the effective reproduction number of test positive cases over time.
Comment on: SARS-CoV-2 infection and transmission in educational settings: a prospective, cross-sectional analysis of infection clusters and outbreaks in England
We evaluated the impact of mass testing in Slovakia, in combination with other measures put in place around the time, by comparing infection prevalence in each round of testing.
Using data on twice weekly PCR testing of front-line healthcare workers, we estimated individual infection times and probability of testing PCR positive through time since infection.
Here we assess the merit of using lateral flow antigen (LFA) tests to allow for a shorter quarantine period by testing at its end, or to replace quarantine altogether by testing daily upon tracing and isolating only when test-positive.
Using reported data on COVID-19 cases and fatalities globally, we estimated the proportion of symptomatic cases that were reported in 210 countries and territories. We then use these estimates to attempt to reconstruct the pandemic.
We evaluated if Facebook for Good mobility data can provide information about movements within the UK during intervention periods and afterward.
To determine if interventions aimed at air travellers can delay establishment of a SARS-CoV-2 outbreak in a previously unaffected country with no shared border with China.
We simulated potential response strategies to assess their effectiveness in three African countries: Niger, Nigeria, and Mauritius.
We estimated the contribution of asymptomatic individuals in spreading COVID-19.
We used an age-structured dynamic-transmission and economic model to explore different scenarios of immunisation programmes over ten years.
Assessing temporal variations in transmission in different countries is essential for monitoring the epidemic, evaluating the effectiveness of public health interventions and estimating the impact of changes in policy.
Using a corrected case fatality ratio, we calculate estimates of the level of under-reporting for any country with greater than ten deaths
We evaluated routine surveillance/ testing strategies that can act as early warning systems in China.
We evaluated the effectiveness of the cordon sanitaire in Wuhan to delay or prevent outbreaks of COVID-19 in other major cities in mainland China.
We assessed the effectiveness of 13 groups of non-pharmaceutical interventions in reducing SARS-CoV-2 transmission using panel analysis and time-series clustering.
We update the synthetic contact matrices with the most recent data, comparing them to measured contact matrices, and develop customised contact matrices for rural and urban settings. We use these to explore the effects of physical distancing interventions for the COVID-19 pandemic in a transmission model.
We explored the potential of combining backward contact tracing with more conventional forward contact tracing for control of COVID-19.
We simulated the arrival of travellers infected with SARS-CoV-2 from the EU and USA to the UK. We assessed the performance of various testing and screening policies in terms of reducing the number of travellers released while still infectious and the number of days they remain infectious.
To compare the health benefits of sustaining routine childhood immunisation in Africa with the risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection through visiting routine vaccination service delivery points.
Using flight data, prevalence estimates and incidence estimates combined, we calculate the ratio of expected imported cases and local incidence globally.
Simulated isolation, tracing and quarantine control strategies for SARS-CoV-2 in a real-world social network generated from high resolution GPS data.
Systematic review of available literature and media reports to find clusters and extract settings type information.
We estimated the age-specific susceptibility to infection and probability of showing clinical symptoms.
The risk of severe COVID-19 disease is known to be higher in older individuals and those with underlying health conditions. Understanding the number of individuals at increased risk of severe COVID-19 illness, and how this varies between countries is needed to inform the design of possible strategies to shield those at highest risk. We evaluated the global prevalence of underlying conditions associated with severe COVID-19 disease.
We compare the relative importance of COVID-19-related reductions in social contacts and health service delivery on TB burden
We use a stochastic age-structured transmission model to explore a range of COVID-19 intervention scenarios in the UK, including the introduction of school closures, social distancing, shielding of elderly groups, self-isolation of symptomatic cases, and extreme "lockdown"-type restrictions.
Projected epidemics in LMIC with and without interventions
We consider expanding the social bubble of either all households or only single occupance households or households with young children. We assess how the implementation of these strategies during lockdown impacts on the risk for Covid-19 resugence.
We analyse social contact data from Kenyan informal settlements to estimate if COVID-19 control measures have affected disease transmission, and economic and food security
We analyse publicly available data on self-reported COVID-19 symptoms and deaths in England
Combining novel setting-specific social contact data from over 40,000 individuals in the UK with a mathematical model of COVID transmission, we compare the potential effects of isolation, contact tracing and physical distancing measures on epidemic control.
Interactive dashboard of Facebook colocation data
We estimate timing of hitting particular case numbers by country in Africa.
We examined human movement on multiple geographic scales to provide a complete picture of the overall dynamics while drawing links to their public health implications.
We used critical care admissions in the United Kingdom to evaluate the number of cases and rate of spread for COVID-19 prior to the lockdown on 23 March 2020
We undertook a systematic review to look at the duration of hospital and ICU stay for patients with COVID-19
We evaluated the potential benefits of other respiratory infectious disease vaccines in the context of the COVID-19 pandemic.
We present the first results of an ongoing survey (CoMix) to track social contact behaviour during the Covid-19 pandemic, and compare social mixing to patterns found in a previous survey.
We evaluated the overdispersion in the number of secondary transmissions of COVID-19
To identify changes in the reproduction number, rate of spread, and doubling time during the course of the COVID-19 outbreak whilst accounting for potential biases due to delays in case reporting.
To identify changes in the reproduction number, rate of spread, and doubling time during the course of the COVID-19 outbreak in Italy whilst accounting for potential biases due to delays in case reporting.
We estimate critical care bed demand for COVID-19 cases in England for the next two weeks. Results suggest that current capacity might be reached or exceeded by the end of March 2020.
We discussed the current evidence on the role of climate on COVID-19 transmission.
Adjusting for delay from confirmation-to-death, we estimated case and infection fatality ratios (CFR, IFR) for COVID-19 on the Diamond Princess ship
To assess the impact of a range of control measures that reduce social mixing on data from the COVID-19 outbreak in Wuhan, China.
We estimate the proportion of observed cases that may have been caused by during the pre-symptomatic period of the corresponding primary cases.
We infer the number of COVID-19 cases based on recently reported deaths. Results suggest that by the time a single COVID-19 death is reported, hundreds to thousands of cases may already be present in the population.
To assess the viability of isolation and contact tracing to control transmission from imported cases of 2019-nCoV.
To understand how human-to-human transmission varied in Wuhan during the early stages of the 2019-2020 COVID-19 outbreak.
We evaluated effectiveness of thermal passenger screening for 2019-nCoV infection at airport exit and entry to inform public health decision-making.
The transmissibility of novel Coronavirus in the early stages of the 2019-20 outbreak in Wuhan: Exploring initial point-source exposure sizes and durations using scenario analysis
To identify changes in the reproduction number during the course of the outbreak. This analysis will be updated with new data as the epidemic progresses.